Multi-Scale Mechanical Testing of Sulfide Solid Electrolytes: From Single Particles to Pellets

Le résumé fourni par la source

The formation and long-term retention of intimate solid–solid interfaces are key requirements for high-performance all-solid-state batteries (ASSBs). In practical cells, interfacial resistance and mechanical degradation are strongly governed by how electrolyte powders consolidate, how cracks initiate, and how contact evolves under stack pressure during assembly and cycling. Sulfide-based solid electrolytes are particularly attractive because they exhibit a “room-temperature pressure sintering” phenomenon 1 , in which particles densify simply by applying pressure at room temperature. This processing route can reduce process energy compared with thermal sintering. In this study, we employ a multi-scale mechanical testing strategy that connects particle-level deformation mechanisms to pellet/rod-level strength in representative sulfide electrolytes. Two typical materials were examined: Li 3 PS 4 glass (LPS) and argyrodite-type Li 6 PS 5 Cl (LPSC). Dynamic densification was measured using a 50 kN universal testing machine and a 3 mm-diameter die at room temperature (~25 °C). To ensure high precision with small specimens, the true specimen deformation was extracted from load–displacement data by compensating for the stiffness of the testing apparatus, enabling reliable relative-density–pressure profiles. Both LPS and LPSC formed highly dense compacts under room-temperature pressing, reaching relative densities above 90%. However, their densification behavior differed: LPS exhibited a lower relative density than LPSC at low applied pressures, whereas LPS achieved a higher relative density than LPSC under high-pressure conditions. Cross-sectional SEM analyses of compacts prepared at different pressures revealed distinct densification mechanisms. Macroscopic strength was evaluated by uniaxial compression of cold-pressed rectangular rods (4 × 4 × 8 mm). LPSC rods fractured at substantially lower compressive stress than LPS rods, indicating that the lower strength and easier crack formation of LPSC contribute to both its compaction behavior and its mechanical stability under stack pressure. Complementary single-particle compression tests show consistent trends at the particle scale and help rationalize the observed compaction and fracture behavior across length scales. The fracture strength is an important facter which control the dentification behavior, The results provide practical guidance for selecting pressure windows, tailoring powder characteristics, and designing composite electrodes that maintain low-resistance interfaces under stack pressure, thereby advancing both electrochemical performance and scalable, low-temperature manufacturing of ASSBs.

Ce résumé expose les affirmations des auteurs. BNTIC ne l’interprète pas comme une validation indépendante des résultats.